This invention relates to piezo-oscillators, and in particular, to a piezo-oscillator in which a piezo-vibrator and oscillating circuit are packaged as a single unit.
Reference is made to FIGS. 1 and 2 wherein a conventional piezo-oscillator utilizing a crystal oscillator which includes a crystal vibrator is shown. In the conventional oscillator, a semiconductor element 41 is connected to lead terminals 43 by fine gold wires 42 by wire bonding. Semiconductor element 41 and lead terminals 43 are packaged in a resin package 50 using the transfer molding method.
A recess 51 is formed by a protrusion of the forming die during the transfer molding process. A crystal vibrator 44 is positioned within recess 51 so that it is aligned with semiconductor element 41 in the longitudinal direction of resin package 50. Crystal vibrator 44 is connected to crystal vibrator connecting lead terminals 45, 46 which are connected to crystal vibrator connecting lead terminals 49 by solder 47. An epoxy resin 48 fills the recess to bury crystal vibrator 44 and is then dried.
These piezo-vibrators have been less than satisfactory. In the conventional oscillator, it becomes necessary for the recess to have a certain minimum thickness resulting in an increase in the package dimensions. Additionally, because the interface between the epoxy resin which fills the recess and the transfer molded resin is large, water may penetrate the interface causing abnormal operation of the piezo-vibrator.
Accordingly, it is desireable to provide a piezo-oscillator which overcomes the shortcomings of the prior art device described above.